ESP8266 Community Forum

- Mon Mar 05, 2018 8:14 pm #74394 Will do, I'll drop the value down.

Anybody else see any other issues?

Is it OK to leave the unconnected pins floating?

-Dave

- Mon Mar 05, 2018 10:32 pm #74397

Is it OK to leave the unconnected pins floating?

It is a good practice to enable the pull up resistors on a pin that is left floating. That or setting the pin as an output.

If the pin is left floating it can be at a state where it is seeing transitions. Usually that is not too big a problem but it would have to get a proper answer if it matters would mean getting information about it from the chip manufacture. It is just easier to do one of the two methods I stated.

- Tue Mar 06, 2018 6:45 am #74403 Yes, good idea to explicitly set unused pins to INPUT_PULLUP.

The chip itself defaults the pins to INPUT_PULLUP after reset but if using the Arduino environment then that sets them back to INPUT as part of its initialisation code. That is a bit irritating, it would be better to init them to INPUT_PULLUP.

GPIO16 doesn't have INPUT_PULLUP, but can be set to INPUT_PULLDOWN_16

- Tue Mar 06, 2018 7:05 am #74406 and please don't just use resistor between gpio16 and rst. This is not a clean method, especially if one wants to use rst external too. Replace yor 100Ohm resistor by any small schottky diode (cathode towards gpio16).

reason: gpio is strong high during deepsleep, so will rst be with 100Ohm resistor and any flashing circuitry (appart from plain push-button) will have to work against this strong high when trying to reset (pull rst low) the esp.